ZrB2 / SiC / TiB2 ultrahigh-temperature ceramic and preparation method thereof

Abstract

The invention provides ZrB2 / SiC / TiB2 ultrahigh-temperature ceramic and a preparation method thereof, and belongs to the field of ultrahigh-temperature ceramic. The preparation method comprises the following steps: preparing SiC / TiB2 composite particles, modifying and compounding the SiC / TiB2 composite particles, preparing ceramic slurry, forming and calcining. The compounding step comprises the following steps: putting modified SiC / TiB2 composite particles and modified ZrB2 particles into N-methyl pyrrolidone, uniformly stirring, adding 4, 4 '-bismaleimide diphenylmethane, and stirring at 110-115 DEG C for 2.8-3.2 hours to obtain ZrB2 / SiC / TiB2 particles; the ceramic product prepared by the invention is high in interface bonding strength, uniform in internal structure, relatively high in toughness and strength, good in temperature resistance, stable in overall performance and excellent in comprehensive performance.

Description

Technical Field

[0001] The present invention belongs to the field of ultra-high temperature ceramics, and specifically relates to a ZrB 2 / SiC / TiB 2 Ultra-high temperature ceramics and preparation methods thereof. Background Art

[0002] Ultra-high temperature ceramics are a type of ceramic material that can be used for a long time in extremely high temperature environments (usually over 2000°C). This type of ceramic material can still maintain good mechanical properties and antioxidant properties in extremely high temperature environments. With the rapid development of aerospace, high-speed aircraft, and advanced energy, the performance requirements of materials in ultra-high temperature environments are becoming increasingly stringent. The research and development of ultra-high temperature ceramics has become a difficult problem that technicians urgently need to solve. A single ceramic material is often difficult to meet these complex performance requirements, so it has become an inevitable trend to compound ceramic materials with different properties.

[0003] ZGar 2 The ZrB ceramic is one of the most widely studied ultra-high temperature ceramic systems. It has a melting point of up to 3245°C, high hardness, good electrical and thermal conductivity, and can maintain good structural stability in ultra-high temperature environments. 2 Ceramics are easily oxidized to form ZrO in high temperature oxidation environment 2 and B 2 O 3 , where B 2 O 3 It is easy to volatilize at high temperature, which leads to a sharp decline in material performance. In order to improve this problem, SiC is usually added. SiO 2 and B 2 O 3 The borosilicate glass phase is formed to effectively fill the pores on the surface of the material and prevent further diffusion of oxygen, thereby increasing the ZrB 2 The oxidation resistance of ZrB 2 -SiC ceramics have the defects of poor toughness and poor thermal shock resistance; TiB 2 The introduction of ZrB 2 -The defects of SiC ceramics can be eliminated, the sintering performance can be improved, and the electrical and thermal conductivity of composite ceramic materials can be enhanced, and the stability of the product can be enhanced.

[0004] Therefore, ZrB 2 , SiC and TiB 2 The three ceramic materials are combined to achieve complementary performance advantages, making the composite material have both ZrB 2 It has the high melting point and good conductivity of SiC, the oxidation resistance and thermal shock resistance of TiB2 Its high hardness and chemical stability meet the usage requirements in extreme environments such as ultra-high temperature and strong corrosion.

[0005] However, ZrB 2 , SiC and TiB 2 powders have different physical properties, and agglomeration and segregation are likely to occur during the mixing process, making it difficult to achieve uniform dispersion. This will lead to non-uniform internal structure and unstable performance of the composite material, reducing the overall performance of the material. Moreover, ZrB 2 , SiC and TiB 2 all have high melting points and strong covalent bond bindings, making it difficult for atoms to diffuse during the sintering process and difficult to achieve densification. During the composite process, chemical reactions are likely to occur at their interfaces, forming brittle phases and weakening the interfacial bonding strength. In addition, there are certain differences in the thermal expansion coefficients of different materials. During the preparation and use processes, thermal stress will be generated due to temperature changes, which may lead to the generation and expansion of interfacial cracks, further damaging the interfacial bonding and affecting the reliability of the material, thus limiting the temperature resistance performance of the material. Summary of the Invention

[0006] To solve the technical problems existing in the prior art, the present invention provides a preparation method of a ZrB 2 / SiC / TiB 2 ultra-high temperature ceramic. The ultra-high temperature ceramic has high interfacial bonding strength, uniform internal structure, relatively high toughness and strength, good temperature resistance, stable overall performance, and excellent comprehensive performance.

[0007] To address the above technical problems, the present invention adopts the following technical solutions: A preparation method of a ZrB 2 / SiC / TiB 2 ultra-high temperature ceramic, including steps of preparing SiC / TiB 2 composite particles, modifying the SiC / TiB 2 composite particles, compounding, preparing ceramic slurry, and shaping and calcining, specifically as follows: 1. Preparing SiC / TiB 2 composite particles (1) Pretreatment of SiC Place SiC particles in a closed container, introduce 5 - 7 times the mass of 4.8 - 5.2 wt% hydrofluoric acid, raise the temperature to 66 - 70 °C, keep warm for 1.8 - 2.2 h, filter out the solid matter, after washing, then put it into 5 - 8 times the mass of 32 - 37 wt% hydrogen peroxide solution, raise the temperature to 73 - 78 °C, keep warm for 3.0 - 4.0 h. After the heat preservation ends, filter, wash, and dry to obtain pretreated SiC particles; The particle size of the SiC particles is 150 - 170 nm; (2) Coating Put the pretreated SiC particles into the coating solution, add polyvinylpyrrolidone, stir at 32 - 37 °C for 35 - 45 min. After stirring, carry out homogenization treatment. The homogenization time is 4.0 - 6.0 min, and the homogenization pressure is 1.0 - 1.3 MPa. After the homogenization treatment, stir in a constant temperature water bath at 62 - 67 °C, stir at 75 - 85 rpm for 9 - 11 h. After stirring, dry to constant weight at 82 - 87 °C, and then carry out calcination treatment under an argon atmosphere. The calcination temperature is 1480 - 1520 °C, the calcination time is 2.8 - 3.2 h, and the heating rate is 4.8 - 5.2 °C / min. After the calcination, SiC / TiB 2 composite particles; The mass - volume ratio of the pretreated SiC particles, the coating solution, and polyvinylpyrrolidone is 12.5 - 13.4 g:195 - 204 mL:0.6 - 1.0 g; The preparation method of the coating solution is as follows: Add tetrabutyl titanate to anhydrous ethanol, control the addition rate to be 0.1 - 0.3 mL / min, and then add glacial acetic acid, and disperse evenly by ultrasonic to obtain Solution 1; Add trimethyl borate to anhydrous ethanol, control the addition rate to be 0.4 - 0.6 mL / min, and disperse evenly by ultrasonic to obtain Solution 2; Slowly add Solution 2 to Solution 1, control the addition time to be 1.8 - 2.2 h, and then add sucrose. After the addition is completed, stir at 170 - 190 rpm for 3.8 - 4.2 h to obtain the coating solution; In the Solution 1, the volume ratio of anhydrous ethanol, tetrabutyl titanate, and glacial acetic acid is 100:18 - 22:2.6 - 3.2; In the Solution 2, the volume ratio of anhydrous ethanol and trimethyl borate is 100:26 - 32; The volume - mass ratio of Solution 1, Solution 2, and sucrose is 118 - 122 mL:126 - 134 mL:4.7 - 5.3 g.

[0008] 2. Modification of SiC / TiB 2 composite particles Put the SiC / TiB 2 composite particles into the toluene solution, stir evenly, add γ - mercaptopropyltrimethoxysilane, raise the temperature to 62 - 67 °C, keep warm and stir for 2.8 - 3.2 h. After stirring, filter, wash, and dry to obtain modified ZrB 2 particles; The SiC / TiB 2The mass ratio of the composite particles, toluene solution, and γ-mercaptopropyltrimethoxysilane is 11.4 - 12.5:105 - 116:1.0 - 1.4; The mass concentration of the toluene solution is 27 - 32%.

[0009] 3. Composite Put the modified SiC / TiB 2 composite particles and the modified ZrB 2 particles into N-methylpyrrolidone, stir evenly, add 4,4'-bismaleimide diphenylmethane, continue to stir evenly, raise the temperature to 110 - 115 °C at a rate of 0.4 - 0.6 °C / min, keep stirring at 200 - 220 rpm for 2.8 - 3.2 h. After the stirring reaction ends, centrifuge at 3800 - 4200 rpm for 8 - 12 min, discard the supernatant, vacuum dry the precipitate at 58 - 62 °C for 10.0 - 14.0 h, the vacuum degree is 0.01 - 0.03 Pa. After the vacuum drying ends, obtain ZrB 2 / SiC / TiB 2 particles; The mass ratio of the modified SiC / TiB 2 composite particles, the modified ZrB 2 particles, N-methylpyrrolidone, and 4,4'-bismaleimide diphenylmethane is 7.5 - 8.3:7.8 - 8.2:280 - 320:1.0 - 1.5; The preparation method of the modified ZrB 2 particles is as follows: Put the ZrB 2 particles into deionized water, stir evenly, carry out ball milling treatment, the ball milling speed is 140 - 160 rpm, the ball milling time is 37 - 43 min. After the ball milling ends, add 3-aminopropanol, raise the temperature to 62 - 68 °C, continue ball milling for 1.8 - 2.2 h. After the ball milling ends, after centrifugation, wash the precipitate with deionized water, dry it to constant weight at 82 - 87 °C, and obtain the modified ZrB 2 particles; The particle size of the ZrB 2 particles is 130 - 150 nm; The mass ratio of the ZrB 2 particles, deionized water, and 3-aminopropanol is 14 - 16:100:1.5 - 1.7.

[0010] 4. Prepare ceramic slurry Put the ZrB 2 / SiC / TiB 2The particles, polyvinyl alcohol and deionized water are mixed and subjected to ultrasonic dispersion. The ultrasonic power is 200 - 220 W, the ultrasonic frequency is 54 - 56 kHz, and the ultrasonic time is 27 - 32 min to obtain a ceramic slurry; The ZrB 2 / SiC / TiB 2 The mass ratio of the particles, polyvinyl alcohol and deionized water is 48 - 52:1.4 - 1.6:380 - 420.

[0011] 5. Molding and calcination The ceramic slurry is centrifuged, and the precipitate is dried to constant weight at 115 - 125 °C, and then placed in a high - temperature furnace and sintered under an argon atmosphere. The sintering pressure is 28 - 32 MPa. First, it is heated at a rate of 4.5 - 5.5 °C / min to 780 - 820 °C and held for 28 - 32 min, then heated at a rate of 0.8 - 1.2 °C / min to 1900 - 1920 °C and held for 1.0 - 1.3 h, and then cooled at a rate of 0.8 - 1.2 °C / min to 1100 - 1300 °C, and cooled to room temperature with the furnace below 1100 - 1300 °C to obtain ZrB 2 / SiC / TiB 2 ultra - high temperature ceramics.

[0012] An ultra - high temperature ceramic of ZrB 2 / SiC / TiB 2 is prepared by the above - mentioned preparation method.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses ZrB 2 , SiC, TiB 2 as a ceramic matrix to prepare ultra - high temperature ceramics. Specifically, first, surface pretreatment is carried out on SiC to introduce more active sites on the surface of SiC, and then TiB 2 is used to coat SiC. Specifically, tetrabutyl titanate is used as the titanium source and trimethyl borate is used as the boron source. The boron source and the titanium source react to obtain a sol of TiB 2 precursor, which forms a TiO 2 -B 2 O 3 gel layer on the surface of SiC. During the coating process, polyvinylpyrrolidone is added as a dispersant to ensure the uniformity of the coating. Combining with high - temperature treatment under an argon atmosphere, a continuous TiB 2 coating layer is formed on the surface of SiC, improving the interfacial bonding performance, and obtaining SiC / TiB 2 composite particles, which can improve the density of the ceramic product, enhance the mechanical properties and oxidation resistance; in the modification step, mercapto - silane coupling agent is used to treat SiC / TiB2 The composite particles are modified so that their surfaces contain mercapto groups; 4,4'-bismaleimide diphenylmethane and modified ZrB are introduced in the composite step 2 particles, and the modified ZrB 2 particles are obtained by amino-modifying ZrB 2 particles so that amino groups are introduced on their surfaces. 4,4'-bismaleimide diphenylmethane can react with both the amino groups of the modified ZrB 2 particles and the mercapto groups of the modified ZrB 2 particles, promoting the formation of a three-dimensional cross-linked network structure with good interfacial bonding strength and a uniform internal structure, resulting in ZrB 2 / SiC / TiB 2 particles, constructing a multi-component composite structure, improving the density of the product, and further enhancing the ultra-high temperature performance and comprehensive stability of the ceramic; 2. The ultra-high temperature ceramic of ZrB 2 / SiC / TiB 2 prepared by the present invention has a fracture toughness of 13.4 - 13.7 MPa·m 1 / 2 at room temperature and a flexural strength of 648 - 359 MPa; 3. The ultra-high temperature ceramic of ZrB 2 / SiC / TiB 2 prepared by the present invention, at 1800 °C, with an oxy-acetylene ablation for 480 s, has a mass ablation rate of 0.207 - 0.214 mg / s and a linear ablation rate of 0.46 - 0.51 μm / s; 4. The ultra-high temperature ceramic of ZrB 2 / SiC / TiB 2 prepared by the present invention, after being kept static in an air environment at 2000 °C for 120 h, is measured again to have a fracture toughness of 12.3 - 12.8 MPa·m 1 / 2 and a flexural strength of 620 - 636 MPa. Specific Embodiments

[0014] To understand the technical features, objectives, and effects of the present invention more clearly, the specific embodiments of the present invention are now described.

[0015] Example 1 1. Preparation of SiC / TiB 2 composite particles (1)Pretreatment of SiC Place the SiC particles in a sealed container, introduce 6 times the mass of 5.0 wt% hydrofluoric acid, raise the temperature to 68 °C, keep warm for 2.0 h, filter out the solid matter, after washing, then put it into 6 times the mass of 35 wt% hydrogen peroxide solution, raise the temperature to 76 °C, keep warm for 3.5 h, after the heat preservation is over, filter, wash and dry to obtain the pretreated SiC particles; The particle size of the SiC particles is 160 nm; (2)Coating Put 13.0 g of pretreated SiC particles into 200 mL of coating solution, add 0.8 g of polyvinylpyrrolidone, stir at 35 °C for 40 min, after stirring, carry out homogenization treatment, the homogenization time is 5.0 min, the homogenization pressure is 1.2 MPa, after the homogenization treatment is over, stir in a 65 °C constant temperature water bath, stir at 80 rpm for 10 h, after stirring is over, dry to constant weight at 85 °C, and then carry out calcination treatment under an argon atmosphere, the calcination temperature is 1500 °C, the calcination time is 3.0 h, the heating rate is 5.0 °C / min, after the calcination is over, obtain SiC / TiB 2 composite particles; The preparation method of the coating solution is as follows: add 20 mL of tetrabutyl titanate to 100 mL of absolute ethanol, control the addition rate to be 0.2 mL / min, then add 3.0 mL of glacial acetic acid, and disperse evenly by ultrasonic to obtain solution one; add 30 mL of trimethyl borate to 100 mL of absolute ethanol, control the addition rate to be 0.5 mL / min, and disperse evenly by ultrasonic to obtain solution two; slowly add 130 mL of solution two to 123 mL of solution one, control the addition time to be 2.0 h, then add 5.0 g of sucrose, after the addition is completed, stir at 180 rpm for 4.0 h to obtain the coating solution.

[0016] 2. SiC / TiB 2 Composite particle modification Put 12.0 g of SiC / TiB 2 composite particles into 110 g of 30 wt% toluene solution, stir evenly, add 1.2 g of γ-mercaptopropyltrimethoxysilane, raise the temperature to 64 °C, keep warm and stir for 3.0 h, after stirring is over, filter, wash and dry to obtain the modified ZrB 2 particles.

[0017] 3. Composite Put 8.0 g of modified SiC / TiB 2 composite particles and 8.0 g of modified ZrB 2The particles were added to 300 g of N-methylpyrrolidone. After stirring evenly, 1.3 g of 4,4'-bismaleimide diphenylmethane was added, and stirring was continued until evenly mixed. The temperature was raised to 114 °C at a rate of 0.5 °C / min, and stirring was carried out at 210 rpm for 3.0 h. After the stirring reaction was completed, centrifugation was carried out at 4000 rpm for 10 min, and the supernatant was discarded. The precipitate was vacuum dried at 60 °C for 12.0 h, and the vacuum degree was 0.02 Pa. After the vacuum drying was completed, ZrB 2 / SiC / TiB 2 particles were obtained; The preparation method of the modified ZrB 2 particles was as follows: 15 g of ZrB 2 particles were added to 100 g of deionized water. After stirring evenly, ball milling was carried out. The ball milling speed was 150 rpm, and the ball milling time was 40 min. After the ball milling was completed, 1.6 g of 3-aminopropanol was added, and the temperature was raised to 65 °C, and ball milling was continued for 2.0 h. After the ball milling was completed, after centrifugation, the precipitate was washed with deionized water and dried to constant weight at 85 °C to obtain modified ZrB 2 particles; The particle size of the ZrB 2 particles was 140 nm.

[0018] 4. Preparation of ceramic slurry 50 g of ZrB 2 / SiC / TiB 2 particles, 1.5 g of polyvinyl alcohol and 400 g of deionized water were mixed and subjected to ultrasonic dispersion. The ultrasonic power was 210 W, the ultrasonic frequency was 55 kHz, and the ultrasonic time was 30 min to obtain a ceramic slurry.

[0019] 5. Molding and calcination The ceramic slurry was centrifuged, and the precipitate was dried to constant weight at 120 °C, and then placed in a high-temperature furnace and sintered under an argon atmosphere. The sintering pressure was 30 MPa. First, the temperature was raised to 800 °C at a rate of 5.0 °C / min and held for 30 min, then the temperature was raised to 1910 °C at a rate of 1.0 °C / min and held for 1.2 h, and then the temperature was lowered to 1200 °C at a rate of 1.0 °C / min. Below 1200 °C, it was cooled to room temperature with the furnace to obtain ZrB 2 / SiC / TiB 2 ultra-high temperature ceramics.

[0020] Example 2 1. Preparation of SiC / TiB 2 composite particles (1)SiC pretreatment Place the SiC particles in a sealed container, introduce 7 times the mass of 5.2 wt% hydrofluoric acid, raise the temperature to 70 °C, keep the temperature for 2.2 h, filter out the solid matter, after washing, then put it into 8 times the mass of 37 wt% hydrogen peroxide solution, raise the temperature to 78 °C, keep the temperature for 3.0 h. After the heat preservation is completed, filter, wash and dry to obtain the pretreated SiC particles; The particle size of the SiC particles is 170 nm; (2)Coating Put 13.4 g of pretreated SiC particles into 204 mL of coating solution, add 1.0 g of polyvinylpyrrolidone, stir at 37 °C for 35 min. After stirring, carry out homogenization treatment. The homogenization time is 4.0 min and the homogenization pressure is 1.3 MPa. After the homogenization treatment, stir in a constant temperature water bath at 67 °C, stir at 85 rpm for 9 h. After stirring, dry to constant weight at 87 °C, and then carry out calcination treatment under an argon atmosphere. The calcination temperature is 1520 °C, the calcination time is 3.2 h, and the heating rate is 5.2 °C / min. After the calcination is completed, obtain SiC / TiB 2 composite particles; The preparation method of the coating solution is as follows: add 22 mL of tetrabutyl titanate to 100 mL of absolute ethanol, control the addition rate to be 0.3 mL / min, and then add 3.2 mL of glacial acetic acid, and disperse evenly by ultrasonic to obtain solution one; add 32 mL of trimethyl borate to 100 mL of absolute ethanol, control the addition rate to be 0.6 mL / min, and disperse evenly by ultrasonic to obtain solution two; slowly add 134 mL of solution two to 122 mL of solution one, control the addition time to be 2.2 h, and then add 5.3 g of sucrose. After the addition is completed, stir at 190 rpm for 4.2 h to obtain the coating solution.

[0021] 2. SiC / TiB 2 Composite particle modification Put 12.5 g of SiC / TiB 2 composite particles into 116 g of 32 wt% toluene solution, stir evenly, add 1.4 g of γ-mercaptopropyltrimethoxysilane, raise the temperature to 67 °C, keep stirring for 3.2 h. After stirring, filter, wash and dry to obtain the modified ZrB 2 particles.

[0022] 3. Composite Put 8.3 g of modified SiC / TiB 2 composite particles and 7.8 g of modified ZrB 2The particles were added to 320 g of N-methylpyrrolidone. After stirring evenly, 1.5 g of 4,4'-bismaleimide diphenylmethane was added, and stirring was continued until evenly mixed. The temperature was raised to 115 °C at a rate of 0.6 °C / min, and stirring was carried out at 220 rpm for 2.8 h. After the stirring reaction was completed, centrifugation was carried out at 4200 rpm for 8 min, and the supernatant was discarded. The precipitate was vacuum dried at 62 °C for 10.0 h, and the vacuum degree was 0.03 Pa. After the vacuum drying was completed, ZrB 2 / SiC / TiB 2 particles were obtained; The preparation method of the modified ZrB 2 particles was as follows: 16 g of ZrB 2 particles were added to 100 g of deionized water. After stirring evenly, ball milling was carried out. The ball milling speed was 160 rpm, and the ball milling time was 43 min. After the ball milling was completed, 1.7 g of 3-aminopropanol was added, and the temperature was raised to 68 °C, and ball milling was continued for 1.8 h. After the ball milling was completed, after centrifugation, the precipitate was washed with deionized water and dried to constant weight at 87 °C to obtain modified ZrB 2 particles; The particle size of the ZrB 2 particles was 150 nm.

[0023] 4. Preparation of ceramic slurry 52 g of ZrB 2 / SiC / TiB 2 particles, 1.6 g of polyvinyl alcohol and 420 g of deionized water were mixed and subjected to ultrasonic dispersion. The ultrasonic power was 220 W, the ultrasonic frequency was 56 kHz, and the ultrasonic time was 32 min to obtain a ceramic slurry.

[0024] 5. Molding and calcination The ceramic slurry was centrifuged, and the precipitate was dried to constant weight at 125 °C, and then placed in a high-temperature furnace and sintered under an argon atmosphere. The sintering pressure was 32 MPa. First, the temperature was raised to 820 °C at a rate of 5.5 °C / min and held for 32 min, then the temperature was raised to 1920 °C at a rate of 1.2 °C / min and held for 1.0 h, and then the temperature was lowered to 1300 °C at a rate of 1.2 °C / min. It was cooled to room temperature with the furnace below 1300 °C to obtain ZrB 2 / SiC / TiB 2 ultra-high temperature ceramics.

[0025] Example 3 1. Preparation of SiC / TiB 2 composite particles (1)SiC pretreatment Place the SiC particles in a sealed container, introduce 5 times the mass of 4.8 wt% hydrofluoric acid, raise the temperature to 66 °C, hold for 1.8 h, filter out the solid matter, wash it, and then put it into 5 times the mass of 32 wt% hydrogen peroxide solution, raise the temperature to 73 °C, hold for 4.0 h. After the holding is completed, filter, wash and dry to obtain the pretreated SiC particles; The particle size of the SiC particles is 150 nm; (2) Coating Put 12.5 g of pretreated SiC particles into 195 mL of coating solution, add 0.6 g of polyvinylpyrrolidone, stir at 32 °C for 45 min. After stirring, perform homogenization treatment. The homogenization time is 6.0 min and the homogenization pressure is 1.0 MPa. After the homogenization treatment, stir in a constant temperature water bath at 62 °C and stir at 75 rpm for 11 h. After stirring, dry to constant weight at 82 °C, and then perform calcination treatment under an argon atmosphere. The calcination temperature is 1480 °C, the calcination time is 2.8 h, and the heating rate is 4.8 °C / min. After the calcination is completed, obtain SiC / TiB 2 composite particles; The preparation method of the coating solution is as follows: Add 18 mL of tetrabutyl titanate to 100 mL of absolute ethanol, control the addition rate to be 0.1 mL / min, and then add 2.6 mL of glacial acetic acid, and disperse evenly by ultrasonic to obtain Solution 1; Add 28 mL of trimethyl borate to 100 mL of absolute ethanol, control the addition rate to be 0.4 mL / min, and disperse evenly by ultrasonic to obtain Solution 2; Slowly add 126 mL of Solution 2 to 118 mL of Solution 1, control the addition time to be 1.8 h, and then add 4.7 g of sucrose. After the addition is completed, stir at 170 rpm for 3.8 h to obtain the coating solution.

[0026] 2. SiC / TiB 2 Composite particle modification Put 11.4 g of SiC / TiB 2 composite particles into 105 g of 27 wt% toluene solution, stir evenly, add 1.0 g of γ-mercaptopropyltrimethoxysilane, raise the temperature to 62 °C, hold and stir for 2.8 h. After stirring, filter, wash and dry to obtain the modified ZrB 2 particles.

[0027] 3. Composite Put 7.5 g of modified SiC / TiB 2 composite particles and 8.2 g of modified ZrB 2The particles were added to 280 g of N-methylpyrrolidone. After stirring evenly, 1.0 g of 4,4'-bismaleimide diphenylmethane was added, and stirring was continued until evenly mixed. The temperature was raised to 110 °C at a rate of 0.4 °C / min, and stirring was carried out at 200 rpm for 3.2 h. After the stirring reaction was completed, centrifugation was carried out at 3800 rpm for 12 min, and the supernatant was discarded. The precipitate was vacuum dried at 58 °C for 14.0 h, and the vacuum degree was 0.01 Pa. After the vacuum drying was completed, ZrB 2 / SiC / TiB 2 particles; The preparation method of the modified ZrB 2 particles was as follows: 14 g of ZrB 2 particles were added to 100 g of deionized water. After stirring evenly, ball milling was carried out. The ball milling speed was 140 rpm, and the ball milling time was 37 min. After the ball milling was completed, 1.5 g of 3-aminopropanol was added, and the temperature was raised to 62 °C, and ball milling was continued for 2.2 h. After the ball milling was completed, after centrifugation, the precipitate was washed with deionized water and dried to a constant weight at 82 °C to obtain modified ZrB 2 particles; The ZrB 2 particles had a particle size of 130 nm.

[0028] 4. Preparation of ceramic slurry 48 g of ZrB 2 / SiC / TiB 2 particles, 1.4 g of polyvinyl alcohol and 380 g of deionized water were mixed and subjected to ultrasonic dispersion. The ultrasonic power was 200 W, the ultrasonic frequency was 54 kHz, and the ultrasonic time was 27 min to obtain a ceramic slurry.

[0029] 5. Molding and calcination The ceramic slurry was centrifuged, and the precipitate was dried to a constant weight at 115 °C, and then placed in a high-temperature furnace and sintered under an argon atmosphere. The sintering pressure was 28 MPa. First, the temperature was raised to 780 °C at a rate of 4.5 °C / min and held for 28 min, then the temperature was raised to 1900 °C at a rate of 0.8 °C / min and held for 1.3 h, and then the temperature was lowered to 1100 °C at a rate of 0.8 °C / min. It was cooled to room temperature with the furnace below 1100 °C to obtain ZrB 2 / SiC / TiB 2 ultra-high temperature ceramics.

[0030] Comparative Example 1 1. Preparation of SiC / TiB 2 composite particles (1)SiC pretreatment Completely the same as in Example 1; (2)Coating The preparation method of the coating liquid is as follows: add 6.0 g of titanium boride particles to 200 mL of absolute ethanol, stir evenly to obtain the coating liquid; the particle size of the titanium boride particles is 110 nm; the remaining operations are exactly the same.

[0031] SiC / TiB 2 The steps of modifying, compounding, preparing the ceramic slurry and forming and calcining the composite particles are exactly the same as those in Example 1.

[0032] Comparative Example 2 1. Preparation of SiC / TiB 2 Composite particles Are exactly the same as those in Example 1; 2. SiC / TiB 2 Composite particle modification Is exactly the same as that in Example 1; 3. Compounding Put 8.0 g of modified SiC / TiB 2 Composite particles and ZrB 2 Particles into 300 g of N-methylpyrrolidone, stir evenly, discard the supernatant, vacuum dry the precipitate at 60 °C for 12.0 h, the vacuum degree is 0.02 Pa, after the vacuum drying is completed, obtain ZrB 2 / SiC / TiB 2 Particles; The ZrB 2 Particles have a particle size of 140 nm.

[0033] The steps of preparing the ceramic slurry and forming and calcining are exactly the same as those in Example 1.

[0034] Performance test Perform performance tests on the ultra-high temperature ceramic products prepared in Examples 1-3 and Comparative Examples 1-2, and the test results are as follows:

[0035] The present invention uses ZrB 2 , SiC, TiB 2 As the ceramic matrix to prepare ultra-high temperature ceramics. Specifically, first perform surface pretreatment on SiC to introduce more active sites on the surface of SiC, and then use TiB 2 To coat SiC. Specifically, tetrabutyl titanate is used as the titanium source and trimethyl borate is used as the boron source. The boron source and the titanium source react to obtain the sol of the TiB 2 Precursor, which forms TiO 2 -B 2 O 3Gel layer, in the coating process, adding polyvinyl pyrrolidone as a dispersant can ensure the uniformity of the coating, combined with high temperature treatment under argon atmosphere, a continuous TiB 2 The coating layer improves the interface bonding performance and obtains SiC / TiB 2 Composite particles can improve the density of ceramic products, enhance mechanical properties and antioxidant properties; in the modification step, mercaptosilane coupling agent is used to modify SiC / TiB 2 The composite particles are modified so that their surfaces contain thiol groups; 4,4'-bismaleimide diphenylmethane and modified ZrB are introduced in the composite step 2 Granular, modified ZrB 2 The particles are ZrB 2 The particles are amino-modified to introduce amino groups on their surface. 4,4'-bismaleimide diphenylmethane can be simultaneously modified with ZrB 2 Amino-modified ZrB particles 2 The thiol groups of the particles react to form a three-dimensional cross-linked network structure with good interface bonding strength and uniform internal structure, resulting in ZrB 2 / SiC / TiB 2 The particles build a multi-component composite structure, which improves the density of the product and further enhances the ultra-high temperature performance and comprehensive stability of the ceramic.

[0036] In Comparative Example 1, titanium boride is directly mixed with pre-treated silicon carbide, which has poor interface compatibility with silicon carbide particles and poor dispersibility, so that the bonding force between the two is weak, which will affect the homogeneity of the ceramic slurry and ultimately affect the internal uniformity of the ceramic product, resulting in poor mechanical properties and toughness, poor heat resistance, and unstable comprehensive performance. In Comparative Example 2, in the compounding step, the modified SiC / TiB 2 Composite particles and ZrB 2 The particles are directly mixed, which will make the modified SiC / TiB 2 Composite particles and ZrB 2 The particle mixing degree is uneven, the interface bonding is poor, and 4,4'-bismaleimide diphenylmethane is not introduced for cross-linking reaction, so a stable cross-linking network structure cannot be formed, which ultimately affects the stability and temperature resistance of the ceramic product.

[0037] Unless otherwise specified, all percentages used in the present invention are by mass.

[0038] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing ultra-high temperature ceramics of ZrB2 / SiC / TiB2, characterized in that: The method comprises the steps of preparing SiC / TiB2 composite particles, modifying and compounding the SiC / TiB2 composite particles, preparing ceramic slurry, and forming and calcining. The preparation of SiC / TiB2 composite particles includes SiC pretreatment and coating steps; The coating step comprises: putting the pre-treated SiC particles into the coating liquid, adding polyvinyl pyrrolidone, stirring and homogenizing, reacting in a constant temperature water bath of 62-67° C., drying and calcining to obtain SiC / TiB2 composite particles; The coating liquid is prepared by adding tetrabutyl titanate and glacial acetic acid to anhydrous ethanol to obtain solution one; adding trimethyl borate to anhydrous ethanol to obtain solution two; adding solution two to solution one, controlling the adding time to be 1.8-2.2h, and then adding sucrose to obtain a coating liquid; The composite step is to put the modified SiC / TiB2 composite particles and the modified ZrB2 particles into N-methylpyrrolidone, stir them evenly, add 4,4'-bismaleimide diphenylmethane, stir them at 110-115°C for 2.8-3.2h, and obtain ZrB2 / SiC / TiB2 particles.

2. The method for preparing a ZrB2 / SiC / TiB2 ultrahigh temperature ceramic according to claim 1, characterized in that: The SiC particle pretreatment step comprises placing the SiC particles in a sealed container, introducing 5-7 times the mass of 4.8-5.2wt% hydrofluoric acid, raising the temperature to 66-70°C, keeping the temperature for 1.8-2.2h, filtering out solids, washing, and then placing the solids in 5-8 times the mass of 32-37wt% hydrogen peroxide solution, raising the temperature to 73-78°C, keeping the temperature for 3.0-4.0h, and filtering, washing, and drying after the end of the insulation to obtain pretreated SiC particles; The particle size of the SiC particles is 150-170 nm.

3. The method for preparing a ZrB2 / SiC / TiB2 ultrahigh temperature ceramic according to claim 1, characterized in that: The coating step comprises: putting the pre-treated SiC particles into the coating liquid, adding polyvinyl pyrrolidone, stirring at 32-37° C. for 35-45 min, performing homogenization after the stirring, the homogenization time is 4.0-6.0 min, the homogenization pressure is 1.0-1.3 MPa, stirring in a constant temperature water bath at 62-67° C., stirring at 75-85 rpm for 9-11 h, drying to constant weight at 82-87° C. after the stirring, and then calcining in an argon atmosphere, the calcination temperature is 1480-1520° C., the calcination time is 2.8-3.2 h, the heating rate is 4.8-5.2° C. / min, and after the calcination, SiC / TiB2 composite particles are obtained; The mass volume ratio of the pre-treated SiC particles, the coating liquid and the polyvinyl pyrrolidone is 12.5-13.4 g: 195-204 mL: 0.6-1.0 g.

4. The method for preparing a ZrB2 / SiC / TiB2 ultrahigh temperature ceramic according to claim 1, characterized in that: The preparation method of the coating liquid comprises the following steps: adding tetrabutyl titanate to anhydrous ethanol, controlling the addition rate to be 0.1-0.3 mL / min, then adding glacial acetic acid, and uniformly dispersing by ultrasonication to obtain solution one; adding trimethyl borate to anhydrous ethanol, controlling the addition rate to be 0.4-0.6 mL / min, and uniformly dispersing by ultrasonication to obtain solution two; slowly adding solution two to solution one, controlling the addition time to be 1.8-2.2 h, and then adding sucrose, and after the addition is completed, stirring at 170-190 rpm for 3.8-4.2 h to obtain the coating liquid; In the solution 1, the volume ratio of anhydrous ethanol, tetrabutyl titanate, and glacial acetic acid is 100:18-22:2.6-3.2; In the second solution, the volume ratio of anhydrous ethanol to trimethyl borate is 100:26-32; The volume mass ratio of solution one to solution two and sucrose is 118-122 mL:126-134 mL:4.7-5.3 g.

5. The method for preparing a ZrB2 / SiC / TiB2 ultrahigh temperature ceramic according to claim 1, characterized in that: The SiC / TiB2 composite particle modification step is to put the SiC / TiB2 composite particles into a toluene solution, stir evenly, add γ-mercaptopropyltrimethoxysilane, raise the temperature to 62-67° C., keep stirring for 2.8-3.2 hours, filter, wash and dry after stirring to obtain modified ZrB2 particles; The mass ratio of the SiC / TiB2 composite particles, the toluene solution, and γ-mercaptopropyltrimethoxysilane is 11.4-12.5:105-116:1.0-1.4; The mass concentration of the toluene solution is 27-32%.

6. The method for preparing a ZrB2 / SiC / TiB2 ultrahigh temperature ceramic according to claim 1, characterized in that: The composite step comprises: putting the modified SiC / TiB2 composite particles and the modified ZrB2 particles into N-methylpyrrolidone, stirring evenly, adding 4,4'-bismaleimide diphenylmethane, continuing to stir evenly, raising the temperature to 110-115°C at a rate of 0.4-0.6°C / min, and stirring at 200-220rpm for 2.8-3.2h. After the stirring reaction is completed, centrifuging and discarding the supernatant, vacuum drying, and obtaining ZrB2 / SiC / TiB2 particles; The mass ratio of the modified SiC / TiB2 composite particles, the modified ZrB2 particles, N-methylpyrrolidone and 4,4'-bismaleimide diphenylmethane is 7.5-8.3:7.8-8.2:280-320:1.0-1.

5.

7. The method for preparing a ZrB2 / SiC / TiB2 ultrahigh temperature ceramic according to claim 6, characterized in that: The preparation method of the modified ZrB2 particles is as follows: ZrB2 particles are put into deionized water, stirred evenly, and then ball-milled at a ball-milling speed of 140-160 rpm for 37-43 min. After the ball-milling, 3-aminopropanol is added, the temperature is raised to 62-68° C., and the ball-milling is continued for 1.8-2.2 h. After the ball-milling, the precipitate is washed with deionized water after centrifugation, and dried to constant weight to obtain the modified ZrB2 particles. The particle size of the ZrB2 particles is 130-150 nm; The mass ratio of the ZrB2 particles, deionized water and 3-aminopropanol is 14-16:100:1.5-1.

7.

8. The method for preparing a ZrB2 / SiC / TiB2 ultrahigh temperature ceramic according to claim 1, characterized in that: The step of preparing the ceramic slurry is to mix ZrB2 / SiC / TiB2 particles, polyvinyl alcohol and deionized water, and perform ultrasonic dispersion, with an ultrasonic power of 200-220W, an ultrasonic frequency of 54-56kHz, and an ultrasonic time of 27-32min to obtain a ceramic slurry; The mass ratio of the ZrB2 / SiC / TiB2 particles, polyvinyl alcohol and deionized water is 48-52:1.4-1.6:380-420.

9. The method for preparing a ZrB2 / SiC / TiB2 ultrahigh temperature ceramic according to claim 1, characterized in that: The forming and calcining steps are as follows: centrifuge the ceramic slurry, dry the precipitate at 115-125°C to constant weight, then put it into a high-temperature furnace, and sinter it in an argon atmosphere at a sintering pressure of 28-32MPa. First, heat it to 780-820°C at a rate of 4.5-5.5°C / min, keep it warm for 28-32min, then heat it to 1900-1920°C at a rate of 0.8-1.2°C / min, keep it warm for 1.0-1.3h, then reduce the temperature to 1100-1300°C at a rate of 0.8-1.2°C / min, and cool it to room temperature below 1100-1300°C in the furnace to obtain ultra-high temperature ceramics of ZrB2 / SiC / TiB2.

10. An ultra-high temperature ceramic of ZrB2 / SiC / TiB2, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.

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